Engage automatically tracks the following events in your store
Added To Cart
Removed From Cart
All of the above events can be used to define your audience for remarketing. For example, to run a campaign to re-engage with visitors that started the checkout process.
You need to receive a few data points on the event before it can be used in custom audiences.
Create a custom audience
In your Facebook account, head to Events manager, select your Pixel and click Create. Select Create Custom Audience.
Walk through the on screen wizard and select Create an Ad when the option appears.
Create your Campaign and make sure your audience is listed in the audience section.
Thats it! You are now targeting a custom audience with your Facebook ads. In this case you created a campaign for remarketing, but as you can see you can create and use a lot of different audiences to reach your customers.